import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory
import os

import launch_ros.parameter_descriptions

def generate_launch_description():
    # 获取默认的urdf路径
    urdf_package_path = get_package_share_directory('fishbot_description')
    default_urdf_path = os.path.join(urdf_package_path,'urdf','fishbot/fishbot.urdf.xacro')
    default_rviz_config_path = os.path.join(urdf_package_path,'config','display_robot_model.rviz')
    #申明一个urdf的参数,方便以后修改
    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name = 'model',default_value=str(default_urdf_path),description='加载的模型文件路径'
    )
    # 通过文件路径，获取内容，并转换成参数值对象，以供传入 robot_state_publisher
    substitution_command_result = launch.substitutions.Command(['xacro ',launch.substitutions.
                                 LaunchConfiguration('model'
    )])
    robot_description_value = launch_ros.parameter_descriptions.ParameterValue(substitution_command_result,
                                                     value_type=str)

    action_robot_static_publisher = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description_value}]  #传递信息的键值对
    )
    action_joint_static_publisher = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
    )
    action_rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d', default_rviz_config_path]   #命令行添加数组里面的shell命令
    )
    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        action_robot_static_publisher,
        action_joint_static_publisher,
        action_rviz_node
    ])